1. Field of the Invention
This invention relates to measurement methods and apparatus. In particular, but not exclusively, the invention relates to methods and apparatus useful in the measurement of the time of flight of a signal, or distance travelled by a signal.
2. Description of the Relevant Art
There are many instances where it is useful to determine the time of flight of a signal. For example, where the speed of sound in a particular medium, such as air or water, is known, the time of flight of an acoustic signal through the medium between a signal transmitter and a signal receiver may be used to determine the distance travelled by the signal. While such measurement techniques are well known, for example in surveying tools, it can be difficult to achieve accurate results.